The production of needles from wire stock involves many processes and different types of machinery in order to prepare quality needles. These varying processes and machinery become more critical in the preparation of surgical needles where the environment of intended use is in humans or animals. Some of the processes involved in the production of surgical grade needles include, straightening spooled wire stock, cutting needle blanks from raw wire stock, tapering or grinding points on one end of the blank stock, providing a bore for receiving suture thread at the other end of the blank stock, imparting flat pressed surfaces on opposite sides of the blank by flat pressing a portion of the needle blank to facilitate grasping by surgical instrumentation and the curving of the needle where curved needles are desired. Additional processing may be done to impart flat surfaces substantially perpendicular to the flat pressed portions of the needle blank by side pressing a portion of the needle blank to further facilitate grasping by surgical instrumentation and insertion into humans or animals. Conventional needle processing is, in large part, a labor intensive operation requiring highly skilled labor. Generally, extreme care must be taken to insure that only the intended working of the needle is performed and the other parts of the needle remain undisturbed. Curved rectangular bodied needles have advantages over other needle configurations in many surgical procedures for a variety of reasons including, uniformity of entry depth for multiple sutures and proper "bite" of tissue surrounding the incision or wound. When providing curved bodied needles for surgical procedures, it is desirable for the needles to have a specified cross section and a specified curvature, i.e., a predetermined radius of curvature. The desired cross section and radius of curvature for the finished needle varies with specific applications as is known in the art.
Known methods of forming curved rectangular bodied needles require several separate and distinct operations to be performed on various machinery. The needle blank after having been cut from straightened wire stock must be flat pressed to impart opposed flat surfaces along body portions located between a tapered point end and a drilled end of the needle blanks. After flat pressing to form opposed flat surfaces on the needle blank, the needle can then be taken from the flat press dies to a curving machine to impart the proper curvature to the needle blank. Optionally, the flat pressing and curving of the needle blank may be accomplished in one step with some available curving die equipment. Care must be taken when removing the blanks from the flat press dies and the curving machinery to avoid disturbing the flat surfaces imparted to the needle blank. After the curving and flat pressing the needle blanks, the needle can then be taken from the curving anvil or die to a side press station to impart flat surfaces substantially perpendicular to the opposed flat surfaces previously formed to give the final rectangular cross sectional profile to the needle body. Again, care must be taken during removal of the needle blanks from the curving anvil and during side flat pressing so as to avoid disturbing the previously imparted opposed flat surface and curved portions of the needle blank.
When needles are made of steel or similar resilient materials, the anvil, die or mandrel used to impart curvature to the needle should have a smaller radius than the radius desired in the final needle product. This configuration allows for some springback after the bending operation and insures that the desired radius of curvature is obtained. Disclosure of such features may be found in U.S. Pat. No. 4,534,771. Previously flattened surgical needles improperly positioned on the anvil for curving may result in a deformation of the previously imparted opposed flat surfaces and may have to be reprocessed or discarded.
One disadvantage to the conventional needle forming techniques noted above is that typically only one needle processing operation at a time, such as, for example, wire straightening, blank cutting, sharpening, boring, flat pressing, curving, can be performed on a single piece of machinery. A further disadvantage is the long processing time required to produce such a needle and the high cost associated with forming and transporting the needles between the various machinery. Lastly, a still further disadvantage is the need to readjust numerous pieces of machinery to process needles of varying length and diameters which further increases production tooling down time and production costs. Therefore, a need exists for a surgical needle forming process that is capable of eliminating one or more processing operations such as flat wire straightening, blank cutting, flat pressing, curving, or side pressing needle blanks. It is also desirable to provide a method of forming curved bodied needles which reduces the time required to produce such needles and the associated costs. It is also desirable to provide a process for producing curved bodied needles which decreases material handling demands.